Atomizing nozzle assembly

ABSTRACT

Liquid (e.g., paint) is sprayed with a nozzle having an axial flow passage and coaxial radial holes into the passage spaced 180* apart intermediate the nozzle inlet and outlet.

United States Patent [1 1 Hughes 51 Aug. 7, 1973 1 ATOMIZING NOZZLEASSEMBLY [75] Inventor: Nathaniel Hughes, Beverly Hills,

Calif.

[73] Assignee: Energy Sciences Incorporated, El Segundo, Calif.

[22] Filed: Sept. 2, 1971 121] App]. No.: 177,280

152] US. Cl 239/11, 239/102, 239/428, 239/596, 239/600 [51] Int. Cl F23d11/16 [58] Field of Search 239/8, 9, 11, 102, 239/424.5, 427, 427.3,428,543, 544, 545, 600, 419, 596

[56] References Cited UNITED STATES PATENTS 3,542,291 11/1970 Hughes239/8 3,531,048 9/1970 Hughes 239/102 X 2,499,092 2/1950 Bumam 239/5443,608,832 9/1971 Hughes 239/102 X 3,618,863 ll/l971 Hughes 239/102 XPrimary ExaminerM. Henson Wood, .lr. Assistant ExaminerMichael MarAttorney-Wm. W. Rymer [57] ABSTRACT Liquid (e.g., paint) is sprayed witha nozzle having an axial flow passage and coaxial radial holes into thepassage spaced 180 apart intermediate the nozzle inlet and outlet.

10 Claims, 2 Drawing Figures PMENIEBAUB H975 ATOMIZING NOZZLE ASSEMBLYThis invention relates to spraying liquid, especially paint.

Objects of the invention are to provide an improved sprayer in whicheven very heavy liquid can be finely atomized and yet which can beoperated at low liquid and air pressures and with low air consumption,and is simple, reliable, self-cleaning, and inexpensive to make and use.Other objects include provision of a wide, fanshaped spray of uniformqualities, so that, e.g., paint can be applied to even a smooth,non-porous surface in a thin, smooth, fast drying, tightly adhered coat,all without requiring separate air outlets for shaping the spray;reduction of forward momentum and overspray characteristics of thepaint, yet with increase in paint flow capability; provision for controlof the fan dimensions and of solvent removal by adjustment of the airpressure; and provision of a nozzle that is insensitiveto liquidviscosity or to its distance from the work surface, and in which thereare no critical orifices to clog.

The invention in one aspect features spraying paint by providing anatomizing nozzle having a body with inlet and outlets ends and an axialflow passage therebetween, and at least a pair of coaxial radial holesinto the passage spaced 180 apart intermediate the inlet and outletends; and supplying compressed air and paint to the nozzle at the inletend and at the radial.

holes to produce a spray of atomized paint at the outlet end. Inpreferred embodiments air and paint are introduced through a single pairof radial holes to produce a fan-shaped spray the long dimension ofwhich is perpendicular to the common axis of those radial holes; air andpaint are also introduced into the axial passage through a pair ofopenings arranged at the inlet end symmetrically at opposite sides ofthe nozzle axis and respectively angularly aligned with the two radialholes, each opening being shaped as a segment of a circle and having anarea larger than that of a radial hole; air and paint are alsointroduced through an axial hole into the axial passage, the axial holehaving an area less than that of either segment-shaped opening and ofeither radial hole; all air and paint is supplied through a reflectorlocated upstream of the nozzle and having an axial opening and twoadditional openings arranged symmetrically at opposite sides of theaxial opening, the three openings having their centers in a single planeperpendicular to the common axis of the radialholes, there also beingsmall openings in the reflector closely adjacent the axial opening topartially relieve the hydraulic pressure drop thereacross; and thenozzle has a single outlet through a countersink to the axial passage.

In another aspect the invention features producing a fan-shaped spray ofatomized liquid by introducing a compressible fluid into a nozzle withan axial flow passage through a pair of radial holes downstream of thenozzle inlet, the holes having a common axis perpendicular to the longdimension of the fan.

Other objects, features, and advantages of the invention will beapparent from the following description of i a preferred embodimentthereof, taken together with the drawings thereof, inwhich:

FIG. 1 is a view of a conventional paint sprayer moditied to embody theinvention, with the aircap partly broken away, some of the elementsinside the aircap being shown in section; and

,.--FIG. 2 is an exploded perspective view of some of the elements ofFIG. 1.

Conventional paint sprayer head 10, with needle valve paint outlet 12surrounded by air outlets 14, is mounted inside aircap 16, which isadapted to be secured to a conventional compressed air operated spraygun (not shown) by threaded retainer ring 18. Cap 16 has an indicatinggroove 17 (FIG. 2).

Annular flange 20 of nozzle 22 is press-fitted in the downstream end ofaxial bore 24 of cap 16, against flange26 surrounding cap outlet 28(outlet diameter a 0.370 inch).

Disc-shaped reflector 30 (outside diameter 0.496 inch) is press-fittedin counterbore 32 of cap 16, between nozzle 22 and head 10. Reflector 30has a central hole 33 (diameter 0.111 inch) midway between two holes 34(each 0.144 inch in diameter) having axes spaced 0.290 inch and coplanarwith the axis of hole 32. Central hole 33 is concentric with animaginary circle (diameter 0.136 inch)icontaining the centers of fourequally spaced holes "36 (diameter 0.0135 inch) arranged symmetricallyabout the line of centers of holes 33 and 34.

Nozzle 22 has a cylindrical wall 40 (outside diameter 0.346 inch, insidediameter 0.260 inch), open at its outlet end across45 countersink 42,which is surrounded by flange 20. Axial inlet 44 (diameter 0.025 inch)is provided in upstream end wall 46 which is relieved to provide twoopenings 48into the nozzle, each opening 48 having the shape of asegment of a circle. The centers of openings 48 are respectively spacedangularly from the centers of holes 34. Two opposing coaxial radialholes 50 (each of diameter 0.073 inch) through wall 40 are apart andtangentto countersink 42. The centers of inlet 44, openings 48, andholes 50 all lie in a single 'plane which is horizontal when the sprayeris oriented with groove l7 facing up (FIG. 2).

Additional nozzle dimensions are:

Length between downstream face of wall 46 and upstream end ofcountersink 42. 0.148 inch Overall length ofnozzles. 0.209 inch Depth ofcountersink 42. 0.029 inch Width of wall 46 between openings 48. 0.190inch Diameter of bore 24 upstream of flange 20. 0.442 inch In operation,paint, and air at greater than atmospheric pressure are supplied to head10 (held so that groove 17 faces up) in conventional manner andrespectively enter cap 16 through outlets l2 and 14. The

paint passes through hole 33 and most of the air passes through holes34. Holes 36 relieve by about 20% the hydraulic pressure drop acrosshole 33, thus reducing the required paint pressure. Mixing takes placein bore 24, with paint and air in varying proportion passing into thenozzle through inlet 44, openings 48, and holes 50. Nozzle 22 atomizesthe paint, which emerges from outlet 28 in a vertical, fan-shaped sprayof very small droplets, due to the arrangement of holes 50 in a singleopposing pair (although the spray would still be fanshaped if therewere, e.g., a pair of additional radial holes respectively spaced 90from and smaller than holes 50). Reflector 30 minimizes back spraying ofpaint against head It), improves atomization, and, by the arrangement ofholes 34 spaced 90 respectively from holes 50 and openings 48, increasesthe width of the fan.

In a typical operation, paint flow is 23 oz./minute, and air flow is CFMat 60 p.s.i.g. Air consumption decreases as paint flow is increased.

The subject matter disclosed herein relating to the aircap andprovisions therein for mounting the nozzle and the reflector was thejoint invention of Nathaniel Hughes and Edson B. Gould III.

Other embodiments will occur to those skilled in the art and are withinthe following claims.

What is claimed is:

1. The method of spraying paint, comprising providing an atomizingnozzle having a body with inlet and outlet ends and an axial flowpassage extending therebetween, and

at least one pair of coaxial radial holes into said passage spaced 180apart intermediate said ends, and

supplying compressed air and paint to said nozzle at said inlet end andsaid radial holes to produce a spray of atomized paint at said ouletend, wherein said air and paint are introduced through one pair of saidradial holes at a rate greater than through any other pair of saidradial holes, whereby said spray is fan-shaped, the long dimension ofthe fan being perpendicular to the common axis of said radial holes ofsaid one pair.

2. The method of claim 1 wherein air and paint are introduced through asingle coaxial pair only of said radial holes.

3. The method of claim 1 wherein air and paint are introduced through apair of openings into said axial passage at said inlet end arrangedsymmetrically at opposite sides of the nozzle axis and respectivelyangularly aligned with said one pair of radial holes.

4. The method of claim 3 wherein said inlet end openings each have anarea larger than that of a said radial hole of said pair.

5. The method of claim 3 wherein air and paint are additionallyintroduced through an axial inlet hole to said axial passage of arealess than that of either said inlet end opening and either said radialhole of said one pair.

6. The method of claim 1 further comprising the steps of providingopenings in said reflector adjacent said axial opening to partiallyrelieve the hydraulic pressure drop thereacross.

7. The method of claim 3 wherein each said inlet end opening has theshape of a segment of a circle.

8. The method of producing a fan-shaped spray of atomized liquid,comprising,

providing a nozzle having a body defining an axial flow passage havinginlet and outlet ends,

and

at least one pair of coaxial radial holes into said passage spaced apartintermediate said ends, supplying said liquid to said passage, andsupplying a compressible fluid to said radial holes at a rate throughone pair of said holes greater than any corresponding rate for any otherpair of radial holes, whereby said spray is produced at said outlet endwith the long dimension of said fan being perpendicular to the commonaxis of said one pair of holes. 9. The method of spraying paint,comprising providing an atomizing nozzle having a body with inlet andoutlet ends and an axial flow passage extending therebetween, and atleast one pair of coaxial radial holes-into said passage spaced 180apart intermediate said ends, supplying compressed air and paint to saidnozzle at said inlet end and said radial holes to produce a spray ofatomized paint at said outlet end, providing upstream of said nozzle aperforated reflector, supplying said air and paint to said nozzlethrough said reflector, and arranging said reflector so that at leastthe major volume of said air is supplied through zones out of angularalignment with said radial holes of said one pair. 10. The method ofspraying paint, comprising providing an atomizing nozzle having a bodywith inlet and outlet ends and an axial flow passage extendingtherebetween, and at least one pair of coaxial radial holes into saidpassage spaced 180 apart intermediate said ends, supplying compressedair and paint to said nozzle at said inlet end and said radial holes toproduce a spray of atomized paint at said outlet end, providing upstreamof said nozzle a reflector having an axial opening and two additionalopenings arranged symmetrically at opposite sides of said axial opening,the centers of said three openings being in a single plane, arrangingsaid reflector so that said single plane is perpendicular to said commonaxis of said radial holes, and supplying said paint to said nozzlethrough said axial opening and air to said nozzle through each of saidadditional openings.

* a a: a:

1. The method of spraying paint, comprising providing an atomizingnozzle having a body with inlet and outlet ends and an axial flowpassage extending therebetween, and at least one pair of coaxial radialholes into said passage spaced 180* apart intermediate said ends, andsupplying compressed air and paint to said nozzle at said inlet end andsaid radial holes to produce a spray of atomized paint at said ouletend, wherein said air and paint are introduced through one pair of saidradial holes at a rate greater than through any other pair of saidradial holes, whereby said spray is fan-shaped, the long dimension ofthe fan being perpendicular to the common axis of said radial holes ofsaid one pair.
 2. The method of claim 1 wherein air and paint areintroduced through a single coaxial pair only of said radial holes. 3.The method of claim 1 wherein air and paint are introduced through apair of openings into said axial passage at said inlet end arrangedsymmetrically at opposite sides of the nozzle axis and respectivelyangularly aligned with said one pair of radial holes.
 4. The method ofclaim 3 wherein said inlet end openings each have an area larger thanthat of a said radial hole of said pair.
 5. The method of claim 3wherein air and paint are additionally introduced through an axial inlethole to said axial passage of area less than that of either said inletend opening and either said radial hole of said one pair.
 6. The methodof claim 1 further comprising the steps of providing openings in saidreflector adjacent said axial opening to partially relieve the hydraulicpressure drop thereacross.
 7. The method of claim 3 wherein each saidinlet end opening has the shape of a segment of a circle.
 8. The methodof producing a fan-shaped spray of atomized liquid, comprising,providing a nozzle having a body defining an axial flow passage havinginlet and outlet ends, and at least one pair of coaxial radial holesinto said passage spaced 180* apart intermediate said ends, supplyingsaid liquid to said passage, and supplying a compressible fluid to saidradial holes at a rate through one pair of said holes greater than anycorresponding rate for any other pair of radial holes, whereby saidspray is produced at said outlet end with the long dimension of said fanbeing perpendicular to the common axis of said one pair of holes.
 9. Themethod of spraying paint, comprising providing an atomizing nozzlehaving a body with inlet and outlet ends and an axial flow passageextending therebetween, and at least one pair of coaxial radial holesinto said passage spaced 180* apart intermediate said ends, supplyingcompressed air and paint to said nozzle at said inlet end and saidradial holes to produce a spray of atomized paint at said outlet end,providing upstream of said nozzle a perforated reflector, supplying saidair and paint to said nozzle through said reflector, and arranging saidreflector so that at least the major volume of said air is suppliedthrough zones out of angular alignment with said radial holes of saidone pair.
 10. The method of spraying paint, comprising providing anatomizing nozzle having a body with inlet and outlet ends and an axialflow passage extending therebetween, and at least one pair of coaxialradial holes into said passage spaced 180* apart intermediate said ends,supplying compressed air and paint to said nozzle at said inlet end andsaid radial holes to produce a spray of atomized paint at said outletend, providing upstream of said nozzle a reflector having an axialopening and two additional openings arranged symmetrically at oppositesides of said axial opening, the centers of said three openings being ina single plane, Arranging said reflector so that said single plane isperpendicular to said common axis of said radial holes, and supplyingsaid paint to said nozzle through said axial opening and air to saidnozzle through each of said additional openings.